Means preventing the extraction of fuel from the accelerating pump

ABSTRACT

The passage from the accelerating pump cylinder to the mixture conduit of the carburetor is closed by a spring pressed check valve. The portion of the passage between the check valve and the mixture conduit has a vent which prevents the depression in that portion of the passage from becoming great enough to draw fuel past the check valve out of the pump cylinder. When the accelerating pump is actuated, the force of the pumped fuel closes a valve which shuts the vent, and the pumped fuel flows into the mixture conduit.

United States Patent [191 Klutho 1 Apr. 9, 1974 [54] MEANS PREVENTING THE EXTRACTION 2,267,570 12/1941 Markham... 261/34 A OF FUEL FROM THE ACCELERATING 3,347,536 10/1967 Sutton r 261/34 A PUMP 2,207,456 7/1940 Coffey r 261/34 A R24,l34 3/1956 Hieger 261/34 A [75] Inventor: Allyn R. Klutho, St, Louis, Mo, 3,715,108 2/1973 Denton 261/50 A [73] Assignee: ACF Industries, Incorporated, New

Yer-k Primary E.\'ammerT1m R. Miles Attorney, Agent, or FirmEdward l-l. Casey [22] Filed: Apr. 6, 1972 v [21] Appl. No.: 241,774 57] ABSTRACT The passage from the accelerating pump cylinder to [52] Cl 261/34 261/52 261/DIG' the mixture conduit of the carburetor is closed by a Y 261/64'C' spring pressed check valve. The portion of the passage between e check ye d ixture co duit has [58] Flew of Search 261/34 64 56 a vent which prevents the depression in that portion of the passagefrom becoming greatenough to draw fuel [56] References C'ted past the check valve out of the pump cylinder. When UNITED STATES PATENTS the accelerating pumpis actuated, the force of the 3,460,813 8/ 1969 Hieger 261/34 A pumped fuel closes a valve which shuts the vent, and 6 8/1972 h s--. 26 /DIG. 56 the pumped fuel flows into the mixture conduit. 2,635,863 4/1953 Olson 261/34 A 2,406,114 8/1946 Sloane et a. 261/34 A 3 Claims, 4'Drawing [Figures 0 32 5 8) I I 1'! bk 3 7 I) iilf 1 l I 2 5 Z ,II -/"IZ 7 i J I: 28 '46 3 '1 H I 4 37 a p n 4 lo 38 l 9 l 5; L l:-"" I I 16 MEANS PREVENTING THE EXTRACTION OF FUEL FROM THE ACCELERATING PUMP BACKGROUND OF THE INVENTION occur in various types of carburetors. It is accordingly.

a principal object of the invention .to prevent this undesirable fuel flow from the accelerating pump.

SUMMARY OF THE INVENTION According to the invention, a carburetor is provided with an acceleration pump having a' pit or reservoir normally filled with fuel. The pump has a plunger adapted to be operated operation of the accelerator foot pedalto force a charge of fuel through a passage into the mixture conduit of the carburetor. The fuel passage terminates in an opening or a nozzle extending into the mixture conduit. The fuel passage is commonly provided with a'check valve for preventing flow backward to the acceleration pump. The fuel passage nozzle is subjected to the depression in the mixture conduit, which may result from the vacuum created therein or from the velocity of the air passing over the nozzle. In order to prevent the resulting pressure drop in the fuel passage from drawing fuel from the acceleration pump, the invention providesmeans for counteracting the de pression in the fuel passage. Thisis done by providing an air vent to the fuel passage through a spring pressed check valve to permit enough air to enter the fuel passage to substantially destroy the vacuum created therein. When the acceleration pump is activated, the fuel passage check valve is forced open and the check valve for the vent is closed to permit the pumped fuel to be conveyed to the mixture conduit as required. The two check valves may have a commonspring, or the equivalent thereof,-so that the'force opening the fuel passage valve is communicated through the spring to close the vent valve.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an elevation partly broken away of a concentric staged carburetor.

FIG. 2 is a partial sectional view of the check valves and nozzle. said depression and an inner venturi 14. The bottom of mixture conduit 12 is provided with a throttle valve 16, and at the upper end of the mixture conduit there are air valves 17 and 18 anda choke valve 20 within venturi 14. The latter includes a main fuel inlet 22. The carburetor also includes a fuel bowl 24 containing an acceleration pump 26. Pump 26 includes plunger 28 connectedto link 30 and adapted to be turned by pivot 32. Plunger piston 34 moves in a cylinder 36 normally, filled with fuel. Plunger 28 and piston 34'are normally held in their retracted positions by spring38. The pit 40 of cylinder 36 is connected by fuel passage 42, and a chamber 44 to nozzle 46 extending into mixture "conduit 12.Check valve 48 for the fuel passage 42 is provided in chamber 44. The upper sideof chamber 44 has an opening 50 communicatingwith a passage 52 to the atmosphere. Opening or vent 50 is adapted to be closed by ball check valve 54. Spring 7 56 extends between check valves 48 and 54. l

The general operation of the carburetor and acceleration pump shown in FIG. 1 is known to those skilled FIGS. 3 and 4 are partial sectional views showing two other embodiments of the check valves.

DESCRIPTION OF THE PREFERRED EMBODIMENTS in the art. After the engine has been started and throttle valve 16 has been opened to some degree, choke valve 20 will be opened, principally by the pressure difference on the opposite sides thereof. Air valves 17 and 18 close off the space between venturi cylinder 14 and outer cylinder'of'mixture conduit 12. When throttle valve 16 is opened to a predetermined degree, air valves 17 and 18 begin to open, either because these are unbalanced valves acted on by the pressure difference across them and overcoming a spring or other bias tending to hold the air valves closed, or the air valves may be opened or allowed to open by means connected to the throttle valve. Before the air valves 17 and 18 are opened, the depression in mixture conduit 12 may rise to a rather high level, approaching in some cases the equivalent of 12 inches of water. After the air valves 17 and 18 are opened, the velocity of the air passing over nozzle 46 may produce a high depression thereat, which would tend to draw fuel from pit 40 of the acceleration pump. This is prevented, however, by bleeding 7 enough air through air passage 52 and air vent 50 into chamber 44 to substantially destroy the vacuum which would otherwise be created in chamber 44. Vent valve 54 may be lightly closed or even open when the engine is not running, but, in any event, spring 56 is calibrated so that ball valve 54 will be retracted to an open posi-- tion when an appreciable depression occurs at nozzle 46. Thus the depression at the outer side of nozzle 46 is not communicated to check valve 48, and does not draw fuel from the acceleration pump past check valve 48. On the other hand, when acceleration pump 26 is actuated, fuel moves through fuel passage 42 pushing ball valve 48 upward and communicating a sufficient force through spring 56 to ball valve 54 to close vent 50. The fuel pumped by acceleration pump 26, therefore, passes through chamber 44 and nozzle 46 into the mixture conduit as required. After the stroke of the acceleration pump is completed, ball 48 falls back to its closed position, relieving spring 56 and permitting ture conduit, but also result from the velocity of the air passing over the nozzle of the fuel passage from the acceleration pump. Referring to FIG. l of the drawing, there is shown a carburetor of the concentric staged type having a body 10 including a mixture conduit 12 valve 54 to open vent 50, particularly if a sufficient depression is present at the outlet of nozzle 46.

FIG. 3 shows a modification of the check valves FIG.

7 2. Asindicated in FIG. 3, ball valves 48 and 54 may be replaced by discs 62 and 64 of any suitable fuelresistant material.

FIG. 4 shows still another modification of the check valves in which only the ball 54 FIG. 2 is replaced by a disc 66. Spring 56, FIG, 2, is replaced by a pair of springs 68 and 70 separated by a perforated disc or washer 72 which may be movable upwardly from a shoulder 74. It can be seen that the operationof the arrangements of FIGS. 3 and 4 are very similar to those of FIG. 2, except that the pressure on spring 70 produced by the retraction of disc 66 will not be communicated to ball valve 48 when washer 72 is seated.

I claim:

1. A carburetor for an internal combustion engine comprising a body structure having at least one air/fuel mixture conduit therethrough, a throttle valve mounted across said conduit for movement from an open position to a position closing said conduit, means for supplying fuel to said conduit comprising a main fuel nozzle and a boost venturi positioned around the discharge end of said nozzle, an air valve mounted in the space between said boost venturi and the walls of said mixture conduit, said air valve being normally biased to a closed position whereby air flowing through said carburetor creates a reduced pressure or depression in said mixture conduit below said air valve, an accelerating pump containing fuel, a fuel passage for conveying fuel from said pump to said mixture conduit, an air vent communicating with said fuel passage, upper and lower valve seats in said fuel passage, an accelerating fuel discharge nozzle intermediate said valve seats and a valve assembly in said fuel passage, said valve assembly comprising upper and lower sealing members spaced apart by resilient spacing means, said spacing means having a length such that only one of said sealing members contacts a valve seat at any time, said air vent having a size such that sufficient air is admitted to said fuel passage during normal operation of said carburetor to prevent the saiddepression from drawing fuel from said accelerating pump.

2. Apparatus according to claim 1 wherein said resilient spacing means comprises a single spring.

3. Apparatus according to claim 2 wherein said resilient means comprises upper and lower separate springs abutting opposite sides of a movable plate, 

1. A carburetor for an internal combustion engine comprising a body structure having at least one air/fuel mixture conduit therethrough, a throttle valve mounted across said conduit for movement from an open position to a position closing said conduit, means for supplying fuel to said conduit comprising a main fuel nozzle and a boost venturi positioned around the discharge end of said nozzle, an air valve mounted in the space between said boost venturi and the walls of said mixture conduit, said air valve being normally biased to a closed position whereby air flowing through said carburetor creates a reduced pressure or depression in said mixture conduit below said air valve, an accelerating pump containing fuel, a fuel passage for conveying fuel from said pump to said mixture conduit, an air vent communicating with said fuel passage, upper and lower valve seats in said fuel passage, an accelerating fuel discharge nozzle intermediate said valve seats and a valve assembly in said fuel passage, said valve assembly comprising upper and lower sealing members spaced apart by resilient spacing means, said spacing means having a length such that only one of said sealing members contacts a valve seat at any time, said air vent having a size such that sufficient air is admitted to said fuel passage during normal operation of said carburetor to prevent the said depression from drawing fuel from said accelerating pump.
 2. Apparatus according to claim 1 wherein said resilient spacing means comprises a single spring.
 3. Apparatus according to claim 2 wherein said resilient means comprises upper and lower separate springs abutting opposite sides of a moveable plate. 